Abstract: The luminous flux is an important index in evaluating the energy efficiency of a light source. Small luminous flux meters are a special instrument for measuring luminous flux parameters of light sources such as light emitting diodes and small bulbs. The accuracy of the measurement of the luminous flux directly determines the accuracy of the luminous flux value of a light source. Based on the characteristics of a small-scale optical flux meter, this paper studies and discusses two new calibration methods, namely, illumination method and radiation power method, by analyzing the principles of optical flux measurement and the traditional calibration method of luminous flux. Through the design of an experimental scheme and the establishment of a test platform, the experimental data are studied and analyzed, and the problems needing attention in measurement are summarized, which can shed light on the calibration of such instruments.